1. Field of the Invention
The present invention relates to bolt anchoring devices. More particularly, the present invention relates to a bolt anchoring device including an anchor sleeve received in a pre-drilled bore in a wall of a building or the like and a bolt screwed into the anchor sleeve to expand an inner end of the anchor sleeve and make it engage the inner wall surface of the bore for thereby securing the bolt in the bore.
2. Description of the Related Art
A number of bolt anchoring devices of the kind which are attached to a wall or the like structure after the structure is completed have heretofore been proposed. An example of such a bolt anchoring device is disclosed in Japanese utility model provisional publication No. 62-18413 and includes an anchor sleeve or socket having a split end portion in which a plug having a truncated cone shape is disposed. The anchor sleeve is driven into a bore in a wall together with the plug by means of a special tool. As the plug goes near the bottom of the hole, it spreads or expands the split end portion of the anchor sleeve radially outward for thereby making the anchor sleeve be secured in the bore. A bolt is then screwed into the anchor sleeve to be held or supported thereby. Similar bolt anchoring devices are disclosed in Japanese patent provisional publication Nos. 6-330525 and 6-116953.
Another example of a bolt anchoring device is disclosed in Japanese patent provisional publication No. 59-147110 and includes an anchor sleeve having a split end portion, i.e., an end portion formed with expanding slots or slits. The split end portion has a conical or tapered inner wall surface. An insert or plug is pushed into the anchor sleeve and driven toward the bottom of a bore in which the anchor sleeve is received. By this, the split end portion is spread or expanded so that the anchor sleeve is held fast or secured in the bore. A similar bolt anchoring device is disclosed in Japanese utility model provisional publication No. 5-94333.
The above described prior art bolt anchoring devices require that the anchor sleeve and the plug be driven into the bore by beating or striking to expand the end portion of the anchor sleeve. Thus, in the case of installation or attachment of a metallic part for hanging a picture from a wall or a metallic part for preventing a furniture from falling, there is the possibility that damage or breakage of the wall and its facing or peeling of a wallpaper is liable to be caused, and great shocks, vibrations and noises are caused to give annoyance to the neighbors.
The anchor sleeve adapted to be expanded by striking requires that the bore in a ceiling or the like structure be accurate in depth. If the bore is too deep, a desired pull-out strength cannot be obtained. Further, it is difficult to ascertain the strength with which the anchor sleeve is attached to the structure. If the hole is not accurate in depth, there is caused an irregularity in the length by which the anchor sleeve protrudes outward from the ceiling or the like structure, and therefore the appearance is deteriorated.
When the anchor sleeve is to be driven into the wall or the like structure, a special tool made up of a driving rod having a head portion for pushing the anchor sleeve into the bore, is necessitated, which is inconvenient since expansion of the anchor sleeve cannot be attained without such a special tool.
The prior art anchoring device of the above described type requires three or more parts and it is hard to reduce the number of its constituent parts and therefore its manufacturing cost.
Further, the prior art anchoring device of the above described type have no means for assuredly checking or ascertaining whether the end of the sleeve is expanded completely or desirably and therefore have the possibility that the sleeve is not held fast or secured to the wall or the like structure and easily pulled off from same when the bolt screwed into such an anchor sleeve is subjected to a load.